Vulkan: Add a perf test for pre-rotation code injection A test is added that dispatches a large number of vertex shaders, generating primitives that are all culled. The vertex shaders are simple so that code injected for pre-rotation would make up the majority of the shader code. Bug: angleproject:5478 Change-Id: I75092cb25e6427449251985f56e54f89813dec32 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2615821 Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>